Abstract: Cefixime, a BCS class II drug, is insoluble in water but freely soluble in acetone and in alcohol. The aqueous solubility of cefixime in water is poor and exhibits exceptionally slow and intrinsic dissolution rate. In the present study, cefixime and β-Cyclodextrin (β-CD) solid dispersions were prepared with a view to study the effect and influence of β-CD on the solubility and dissolution rate of this poorly aqueous soluble drug. Phase solubility profile revealed that the solubility of cefixime was increased in the presence of β-CD and was classified as AL-type. Effect of variable, such as drug:carrier ratio, was studied. Physical characterization of the solid dispersion was characterized by Fourier transform infrared spectroscopy (FT-IR) and Differential scanning calorimetry (DSC). These studies revealed that a distinct loss of drug crystallinity in the solid molecular dispersions is ostensibly accounting for enhancement of dissolution rate in distilled water. The drug release from the prepared solid dispersion exhibited a first order kinetics. Solid dispersions of cefixime showed a 6.77 times fold increase in dissolution rate over the pure drug.
Abstract: Electromagnetic Launch (EML) systems have been proposed for military applications to accelerate jet planes on aircraft carriers. This paper proposes the implementation of similar technology to aid civil aircraft take-off, which can provide significant economic, environmental and technical benefits. Assisted launch has the potential of reducing on ground noise and emissions near airports and improving overall aircraft efficiency through reducing engine thrust requirements. This paper presents a take-off performance analysis for an Airbus A320-200 taking off with and without the assistance of the electromagnetic catapult. Assisted take-off allows for a significant reduction in take-off field length, giving more capacity with existing airport footprints and reducing the necessary footprint of new airports, which will both reduce costs and increase the number of suitable sites. The electromagnetic catapult may allow the installation of smaller engines with lower rated thrust. The consequent fuel consumption and operational cost reduction is estimated. The potential of reducing the aircraft operational costs and the runway length required make EML system an attractive solution to the air traffic growth in busy airports.
Abstract: We address the problem of interference over all the channels in multiuser MIMO-OFDM systems. This paper contributes three beamforming strategies designed for multiuser multiple-input and multiple-output by way of orthogonal frequency division multiplexing, in which the transmit and receive beamformers are acquired repetitious by secure-form stages. In the principal case, the transmit (TX) beamformers remain fixed then the receive (RX) beamformers are computed. This eradicates one interference span for every user by means of extruding the transmit beamformers into a null space of relevant channels. Formerly, by gratifying the orthogonality condition to exclude the residual interferences in RX beamformer for every user is done by maximizing the signal-to-noise ratio (SNR). The second case comprises mutually optimizing the TX and RX beamformers from controlled SNR maximization. The outcomes of first case is used here. The third case also includes combined optimization of TX-RX beamformers; however, uses the both controlled SNR and signal-to-interference-plus-noise ratio maximization (SINR). By the standardized channel model for IEEE 802.11n, the proposed simulation experiments offer rapid beamforming and enhanced error performance.
Abstract: Using the quantum kinetic equation for electrons interacting with acoustic phonon, the density of the constant current associated with the drag of charge carriers in cylindrical quantum wire by a linearly polarized electromagnetic wave, a DC electric field and a laser radiation field is calculated. The density of the constant current is studied as a function of the frequency of electromagnetic wave, as well as the frequency of laser field and the basic elements of quantum wire with a parabolic potential. The analytic expression of the constant current density is numerically evaluated and plotted for a specific quantum wires GaAs/AlGaAs to show the dependence of the constant current density on above parameters. All these results of quantum wire compared with bulk semiconductors and superlattices to show the difference.
Abstract: Apolipoprotein E (APOE) gene polymorphism has influence on serum lipids which relates to cardiovascular risk. The purpose of this study was to determine the frequency distribution of APOE alleles among Malaysian Type 2 Diabetes Mellitus (DM) patients with and without coronary artery disease (CAD) and their association with serum lipid profiles. A total of 115 patients were recruited in which 78 patients had Type 2 DM without CAD and 37 patients had Type 2 DM with CAD. The APOE polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The APOE ɛ3 allele was the most common one in both groups. There was no significant association between the APOE genotypes and the CAD status in Type 2 DM using Pearson χ2 test. Further analysis indicated there were no significant differences in all lipid parameters between E2, E3 and E4 subgroups in both groups. The study showed that the E4 allele carriers of Type 2 DM with CAD patients had higher LDL-C level and lower HDL-C level compared to the other allele carriers. However, analyses showed these levels were not statistically different. The study also showed that the Type 2 DM with CAD group with E2 allele had higher triglyceride (TG). In conclusion, further study with larger sample size is needed to confirm role of E4 as a marker of CAD among Type 2 DM patients in Malaysian population.
Abstract: In this study, a sequential deposition process is used for the fabrication of PEDOT: PSS based inverted planar perovskite solar cell. A small amount of additive deionized water (DI-H2O) was added into PbI2 + Dimethyl formamide (DMF) precursor solution in order to increase the solubility of PbI2 in DMF, and finally to manipulate the surface morphology of the perovskite films. A morphology transition from needle like structure to hexagonal plates, and then needle-like again has been observed as the DI-H2O was added continuously (0.0 wt% to 3.0wt%). The latter one leads to full surface coverage of the perovskite, which is essential for high performance solar cell.
Abstract: Recently, copper and manganese-containing systems are recognized as active and selective catalysts in many oxidation reactions. The main idea of this study is to obtain more information about γ-Al2O3 supported Cu-La catalysts and to evaluate their activity to simultaneous oxidation of CO, CH3OH and dimethyl ether (DME). The catalysts were synthesized by impregnation of support with a mixed aqueous solution of nitrates of copper, manganese and lanthanum under different conditions. XRD, HRTEM/EDS, TPR and thermal analysis were performed to investigate catalysts’ bulk and surface properties. The texture characteristics were determined by Quantachrome Instruments NOVA 1200e specific surface area and pore analyzer. The catalytic measurements of single compounds oxidation were carried out on continuous flow equipment with a four-channel isothermal stainless steel reactor in a wide temperature range. On the basis of XRD analysis and HRTEM/EDS, it was concluded that the active component of the mixed Cu-Mn-La/γ–alumina catalysts strongly depends on the Cu/Mn molar ratio and consisted of at least four compounds – CuO, La2O3, MnO2 and Cu1.5Mn1.5O4. A homogeneous distribution of the active component on the carrier surface was found. The chemical composition strongly influenced catalytic properties. This influence was quite variable with regards to the different processes.
Abstract: The present experimental study insights the decontamination of instantaneous velocity fluctuations captured by Acoustic Doppler Velocimeter (ADV) in gravel-bed streams to ascertain near-bed turbulence for low Reynolds number. The interference between incidental and reflected pulses produce spikes in the ADV data especially in the near-bed flow zone and therefore filtering the data are very essential. Nortek’s Vectrino four-receiver ADV probe was used to capture the instantaneous three-dimensional velocity fluctuations over a non-cohesive bed. A spike removal algorithm based on the acceleration threshold method was applied to note the bed roughness and its influence on velocity fluctuations and velocity power spectra in the carrier fluid. The velocity power spectra of despiked signals with a best combination of velocity threshold (VT) and acceleration threshold (AT) are proposed which ascertained velocity power spectra a satisfactory fit with the Kolmogorov “–5/3 scaling-law” in the inertial sub-range. Also, velocity distributions below the roughness crest level fairly follows a third-degree polynomial series.
Abstract: Efficient utilization of spectrum resources is a
fundamental issue of wireless communications due to its scarcity.
To improve the efficiency of spectrum utilization, the spectrum
sharing for unlicensed bands is being regarded as one of key
technologies in the next generation wireless networks. A number
of schemes such as Listen-Before-Talk(LBT) and carrier sensor
adaptive transmission (CSAT) have been suggested from this aspect,
but more efficient sharing schemes are required for improving
spectrum utilization efficiency. This work considers an opportunistic
transmission approach and a dynamic Contention Window (CW)
adjustment scheme for LTE-U users sharing the unlicensed spectrum
with Wi-Fi, in order to enhance the overall system throughput. The
decision criteria for the dynamic adjustment of CW are based on
the collision evaluation, derived from the collision probability of the
system. The overall performance can be improved due to the adaptive
adjustment of the CW. Simulation results show that our proposed
scheme outperforms the Distributed Coordination Function (DCF)
mechanism of IEEE 802.11 MAC.
Abstract: The material behavior of graphene, a single layer of
carbon lattice, is extremely sensitive to its dielectric environment. We
demonstrate improvement in electronic performance of graphene
nanowire interconnects with full encapsulation by lattice-matching,
chemically inert, 2D layered insulator hexagonal boron nitride (h-
BN). A novel layer-based transfer technique is developed to construct
the h-BN/MLG/h-BN heterostructures. The encapsulated graphene
wires are characterized and compared with that on SiO2 or h-BN
substrate without passivating h-BN layer. Significant improvements
in maximum current-carrying density, breakdown threshold, and
power density in encapsulated graphene wires are observed. These
critical improvements are achieved without compromising the carrier
transport characteristics in graphene. Furthermore, graphene wires
exhibit electrical behavior less insensitive to ambient conditions, as
compared with the non-passivated ones. Overall, h-BN/graphene/h-
BN heterostructure presents a robust material platform towards the
implementation of high-speed carbon-based interconnects.
Abstract: The first pn-type carrier-induced silicon Bragg-grating filter is demonstrated. The extinction-ratio modulations are 11.5 dB and 10 dB with reverse and forward biases, respectively. 8-Gpbs data rate is achieved with a reverse bias.
Abstract: Carrier-based methods have been used widely for switching of multilevel inverters due to their simplicity, flexibility and reduced computational requirements compared to space vector modulation (SVM). This paper focuses on Multicarrier Sinusoidal Pulse Width Modulation (MCSPWM) strategy for the three phase Five-Level Flying Capacitor Inverter (5LFCI). The inverter is simulated for Induction Motor (IM) load and Total Harmonic Distortion (THD) for output waveforms is observed for different controlling schemes.
Abstract: Application of nanoscience in biomedical field has come across as a new era. This study involves the synthesis of nano drug carrier with antibiotic loading. Based on the founding that polydopamine (PDA) nanoparticles could be formed via self-polymerization of dopamine at alkaline pH, one-step synthesis of rifampicin coupled polydopamine (PDA-R) nanoparticles was achieved by adding rifampicin into the dopamine solution. The successful yield of PDA nanoparticles with or without the presence of rifampicin during the polymerization process was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. Drug loading was monitored by UV-vis spectroscopy and the loading efficiency of rifampicin was calculated to be 76%. Such highly capacious nano-reservoir was found very stable with little drug leakage at pH 3.
Abstract: This work studies the effect of thickness on structural
and electrical properties of CuAlS2 thin films grown by two stage
vacuum thermal evaporation technique. CuAlS2 thin films of
thicknesses 50nm, 100nm and 200nm were deposited on suitably
cleaned corning 7059 glass substrate at room temperature (RT). In
the first stage Cu-Al precursors were grown at room temperature by
thermal evaporation and in the second stage Cu-Al precursors were
converted to CuAlS2 thin films by sulfurisation under sulfur
atmosphere at the temperature of 673K. The structural properties of
the films were examined by X-ray diffraction (XRD) technique while
electrical properties of the specimens were studied using four point
probe method. The XRD studies revealed that the films are of
crystalline in nature having tetragonal structure. The variations of the
micro-structural parameters, such as crystallite size (D), dislocation
density ( ), and micro-strain ( ), with film thickness were
investigated. The results showed that the crystallite sizes increase as
the thickness of the film increases. The dislocation density and
micro-strain decreases as the thickness increases. The resistivity ( )
of CuAlS2 film is found to decrease with increase in film thickness,
which is related to the increase of carrier concentration with film
thickness. Thus thicker films exhibit the lowest resistivity and high
carrier concentration, implying these are the most conductive films.
Low electrical resistivity and high carrier concentration are widely
used as the essential components in various optoelectronic devices
such as light-emitting diode and photovoltaic cells.
Abstract: In the past years electric mobility became part of a
public discussion. The trend to fully electrified vehicles instead of
vehicles fueled with fossil energy has notably gained momentum.
Today nearly every big car manufacturer produces and sells fully
electrified vehicles, but electrified vehicles are still not as competitive
as conventional powered vehicles. As the traction battery states the
largest cost driver, lowering its price is a crucial objective. In
addition to improvements in product and production processes a nonnegligible,
but widely underestimated cost driver of production can
be found in logistics, since the production technology is not
continuous yet and neither are the logistics systems. This paper presents an approach to evaluate cost factors on
different designs of load carrier systems. Due to numerous
interdependencies, the combination of costs factors for a particular
scenario is not transparent. This is effecting actions for cost reduction
negatively, but still cost reduction is one of the major goals for
simultaneous engineering processes. Therefore a concurrent and
phase appropriate cost valuation method is necessary to serve cost
transparency. In this paper the four phases of this cost valuation
method are defined and explained, which based upon a new approach
integrating the logistics development process in to the integrated
product and process development.
Abstract: Diets high in processed foods have been found to lack
essential micro-nutrients for optimum human development and
overall health. Some micro-nutrients such as copper (Cu) have been
found to enhance the inflammatory response through its oxidative
functions, thereby having a role in cardiovascular disease, metabolic
syndrome, diabetes and related complications. This research study
was designed to determine if food crops could be bio-fortified with
micro-nutrients by growing sprouts on mineral fortified fiber mats. In
the feasibility study described in this contribution, recycled cellulose
fibers and clay, saturated with either micro-nutrient copper ions or
copper nanoparticles, were converted to a novel mineral-cellulose
fiber carrier of essential micro-nutrient and of antimicrobial
properties. Seeds of Medicago sativa (alfalfa), purchased from a
commercial, organic supplier were germinated on engineered
cellulose fiber mats. After the appearance of the first leaves, the
sprouts were dehydrated and analyzed for Cu content. Nutrient
analysis showed ~2 increase in Cu of the sprouts grown on the fiber
mats with copper particles, and ~4 increase on mats with ionic copper
as compared to the control samples. This study illustrates the
potential for the use of engineered mats as a viable way to increase
the micro-nutrient composition of locally-grown food crops and the
need for additional research to determine the uptake, nutritional
implications and risks of micro-nutrient bio-fortification.
Abstract: Various nanomaterials can be used as a drug delivery
vehicles in nanomedicine, called nanocarriers. They can either be
organic or inorganic, synthetic or natural-based. Although synthetic
nanocarriers are easier to produce, they can often be toxic for the
organism and thus not suitable for use in treatment. From naturalbased
nanocarriers, the most commonly used are protein cages or
viral capsids. In this work, virus bacteriophage λ was used for
delivery of different cytotoxic drugs (cisplatin, carboplatin,
oxaliplatin and doxorubicin). Large quantities of phage λ were
obtained from phage λ-producing strain of E. coli cultivated in
medium with 0.2% maltose. After killing of E. coli with chloroform
and its removal by centrifugation, the phage was concentrated by
ultracentrifugation at 130 000×g and 4°C for 3 h. The encapsulation
of the drugs was performed by infusion method and four different
concentrations of the drugs were encapsulated (200; 100; 50; 25
μg·mL-1). Free drug molecules were removed by filtration. The
encapsulation was verified using the absorbance for doxorubicin and
atomic absorption spectrometry for platinum cytostatics. The amount
of encapsulated drug linearly increased with the increasing
concentration of applied drug with the determination coefficient
R2=0.989 for doxorubicin; R2=0.967 for cisplatin; R2=0.989 for
carboplatin and R2=0.996 for oxaliplatin. The overall encapsulation
efficiency was calculated as 50% for doxorubicin; 8% for cisplatin;
6% for carboplatin and 10% for oxaliplatin.
Abstract: This article describes the results of research focused
on quality of railway freight transport services. Improvement of these
services has a crucial importance in customer considering on the
future use of railway transport. Processes filling the customer
demands and output quality assessment were defined as a part of the
research. In this contribution is introduced the map of quality
planning and the algorithm of applied methodology. It characterizes a
model which takes into account characters of transportation with
linking a perception services quality in ordinary and extraordinary
operation. Despite the fact that rail freight transport has its solid
position in the transport market, lots of carriers worldwide have been
experiencing a stagnation for a couple of years. Therefore, specific
results of the research have a significant importance and belong to
numerous initiatives aimed to develop and support railway transport
not only by creating a single railway area or reducing noise but also
by promoting railway services. This contribution is focused also on
the application of dynamic quality models which represent an
innovative method of evaluation quality services. Through this
conception, time factor, expected, and perceived quality in each
moment of the transportation process can be taken into account.
Abstract: Si-Ge solid solutions (bulk poly- and mono-crystalline
samples, thin films) are characterized by high perspectives for
application in semiconductor devices, in particular, optoelectronics
and microelectronics. From this point of view, complex studying of
structural state of the defects and structural-sensitive physical
properties of Si-Ge solid solutions depending on the contents of Si
and Ge components is very important. Present work deals with the
investigations of microstructure, microhardness, internal friction and
shear modulus of Si1-xGex(x≤0,02) bulk monocrystals conducted at
room temperature. Si-Ge bulk crystals were obtained by Czochralski
method in [111] crystallographic direction. Investigated
monocrystalline Si-Ge samples are characterized by p-type
conductivity and carriers’ concentration 5.1014-1.1015cm-3.
Microhardness was studied on Dynamic Ultra Micro hardness Tester
DUH-201S with Berkovich indenter. Investigate samples are characterized with 0,5x0,5x(10-15)mm3
sizes, oriented along [111] direction at torsion oscillations ≈1Hz,
multistage changing of internal friction and shear modulus has been
revealed in an interval of strain amplitude of 10-5-5.10-3. Critical
values of strain amplitude have been determined at which hysteretic
changes of inelastic characteristics and microplasticity are observed. The critical strain amplitude and elasticity limit values are also
determined. Dynamic mechanical characteristics decreasing trend is
shown with increasing Ge content in Si-Ge solid solutions. Observed
changes are discussed from the point of view of interaction of various
dislocations with point defects and their complexes in a real structure
of Si-Ge solid solutions.
Abstract: RF magnetron sputtering is used on the ceramic targets,
each of which contains zinc oxide (ZnO), zinc oxide doped with
aluminum (AZO) and zinc oxide doped with gallium (GZO). The XRD
analysis showed a preferred orientation along the (002) plane for ZnO,
AZO, and GZO films. The AZO film had the best electrical properties;
it had the lowest resistivity of 6.6 × 10-4 cm, the best sheet resistance of
2.2 × 10-1 Ω/square, and the highest carrier concentration of 4.3 × 1020
cm-3, as compared to the ZnO and GZO films.